This grant supports research on a wide range of neoplastic disorders. The program includes studies designed to test hypotheses developed through previous research supported by the grant, as well as developmental and pilot studies. In the study of breast cancer, emphasis is currently on the roles of endogenous and exogenous steroid hormones. The hypothesis that a woman's breast cancer risk is determined, in part, by the proportion of her estrogens metabolized to estriol, is being evaluated by comparison of populations at different risk of cancer of the breast. The role of exogenous hormones (specifically, oral contraceptives and conjugated estrogens given for menopausal symptoms) are being evaluated specifically in the context of risk of breast disease and cancer of the endometrium. Overall mortality is also included in the study of health effects of oral contraceptives. The hypothesis that Hodgkin's disease is transmitted by person-to-person contact is being explored by a study of high school contacts and by the development of a study of the role of tonsillectomy and early childhood environment. Other studies include a case-control study of cancer of the pancreas, a study of the relationship of cystic mastitis to breast cancer mortality, and a study of the relationship of gastric ulcer to gastric cancer. It is planned to expand the case-control study of cancer of the pancreas to include multiple myeloma and ovarian cancer.